Means for suspending lifeboats from gravity davits



Nov. 25, 1952 A. VREUGDENHIL MEANS FOR SUSPENDING LIFEBOATS FROM GRAVITY DAVITS Filed March 10, 1949 Nov. 25, 1952 2,618,792

MEANS FOR SUSPENDING LIFEBOATS FROM GRAVITY DAVI'IS A. VREUGDENHH- 2 SHEETSSHEET 2 Filed March 10, 1949 Patented Nov. 25, 1952 UNITED STATES PATENT OFFICE MEANS FOR SUSPENDING LIFEBOATS FROM GRAVITY DAVITS Adrianus Vreugdenhil, Amsterdam, Netherlands Application March 10, 1949, Serial No. 80,732

Claims.

This invention relates to means for suspending a life boat from a gravity davit, i. e. a davit whose head during its outward movement has a tendency to follow a downwardly inclined path as long as the list of the vessel, if any, does not exceed a predetermined maximum value. More specially the invention is concerned with such means, wherein the top block of the boat fall is suspended from a hook member secured to the davit arm.

In known means of this kind, the hook memher is rigidly secured to, or integral with the davit arm in such manner that, even on the high side of a moderately listed vessel, the block of the boat fall will automatically slip off said member by gravity, when the davit assumes, or nearly assumes, its fully outboard position and the fall is payed out. If, however, the list exceeds the aforesaid maximum value, the blocks of the life boats on the high side of the vesse1 cannot slip off their respective hooks owing to the fact that the latter have an insufficient downward incline towards the water, so that it is impossible to launch said boats.

The invention has for its object so to improve said means that even under the very unfavorable circumstances depicted above it will be possible for the block of the boat gradually to slip ofi the hook member when the fall is payed out. With this object in view, my invention primarily consists herein that the hook member is hinged to the davit arm and associated therewith through releasable means ofiering, when released, a certain amount of resistance to downward swinging movement of the hook member relative to the davit arm.

In order that my invention may be well understood by those skilled in the art, I shall now proceed to describe it with reference to the annexed drawings, which illustrate various embodiments thereof.

Fig. 1 is a diagrammatic side view of a conventional gravity davit in inboard and in outboard position,

Fig. 2 is a side view of the top part of a gravity davit in accordance with my invention,

Fig. 2a is a fragmentary section along the lines 2a-2a of Fig. 2,

Fig. 3 is a side view of the top part of a second embodiment,

Fig. 4 is a side view of the top part of a third embodiment, and

Fig. 5 is a side view of the top part of a fourth embodiment.

In Fig. l, a gravity davit, as known in the prior art, is shown and the numeral 6 designates the deck of a heavily listed vessel, I the runway of a gravity davit mounted on the high side of said vessel, 8 the arm of said davit, 9, II] rollers mounted to the davit foot and adapted to travel in said runway, I I the hook member integral with the head of the davit arm, and I2 the block through which the life boat I3 is suspended from said hook, and 25 a sheave mounted to the davit arm for guiding the boat fall (not shown).

The inboard position of the davit and the boat is drawn in full lines. As shown, the inner or bearing face of the hook member II is upwardly inclined, so that the block I2 cannot disengage the davit, if the boat fall is payed out.

In the extreme outboard position of the davit, illustrated in dotted lines in Fig. 1, the said inner fac would incline towards the water if the vessel had a list of say no more than 15, when it would still be possible to launch the boat by paying out the fall. As shown, however, with a list of say 30, the inner face of the hook member still has a slight upward inclination, so that it is impossible for the block I2 to slide, by gravity, downhill along said member II towards the water, so that the boat cannot be launched.

In accordance with Fig. 2, which only shows the top portion of the davit arm 8 with associate parts, the hook member I I is pivoted to said portion as at It so as to be adapted for swinging motion in a, vertical plane at right angles to the longitudinal axis of the vessel (not shown). Intermediate the free end of the hook member II and the hinge I4, said member is hinged, through a pivot I5 parallel with pivot I4, to a sleeve I6, in which the lower end of a spindle I1 is rotatably mounted but locked against axial movement. The upper portion of this spindl is provided with non-selfbraking screw thread and cooperates with a nut I8 with diametrically opposed studs I9, whose common axis is in parallel relation with the pivots I I and I5, and which are supported in bearings of brackets 20 on the davit arm 8. At its top end, the spindle has a noncircular head 2 I, and a mating ring 22 on a looking member 23, which is pivoted to the davit arm 8 as at 24, is adapted to be swung into locking engagement with said head 2| so as to prevent rotation of spindle I'I.

Assuming now the full lines of Fig. 2 to illustrate the extreme outboard position of the davit 8 and the relative positions of the various parts under said conditions, i. c. with the screw spindle locked against rotation, it will be seen that the block I2, from which the boat (not shown) is supposed to be suspended, cannot slip off the hook member I I under the gravity pull of the boat, for the reason that the inner face of the hook member has a slight upward incline towards the water.

However, if the locking member 23 is swung, by the crew in the boat, into the position shown in dotted lines, the gravity pull of the boat will be transmitted through sleeve it to the spindle ll, which, owing to the relatively high pitch of its screw thread, will thereby be pulled down and thus rotated relative to nut 58, which, obviously, cannot follow said downward motion. Consequently, the hook member H will swing downward about its pivot hi until the head 2| engages the nut 19 and the spindle ll is arrested, when the hook member assumes a position 52', wherein the block can slide downhill along the same when the boat fall, indicated by the dash and dot line 25 and passed over sheave 26 mounted in the davit head, is payed out. It will be understood that the screw spindle i? will rotate slowly, owing to the frictional resistance offered by nut IS, so that the latter acts as a brake, which retards the downward swinging motion of hook member H. Thus the fall 25 will only gradually be loaded and no jerks will occur.

Fig. 3 shows a construction not essentially different from that illustrated in Fig. 2. Here, however, the screw spindle ii is provided at its lower end with a spherical head 2'! engaged by a cup-shaped recess 23 at the inner end of the hook member H, whilst pivot it engages said member intermediate th front and the rear end thereof, so that the gravity pull of the boat,.acting through the top block 12, tends to force the screw spindle in upward direction through its nut l3, which, in this instance, is integral with the davit head. The spindle I! is here provided at its top end with a handwheel 29, rotation of which is normally prevented by a locking member 38 adapted to b swung, by the crew in the boat, into inoperative position, then the spindle El is free to be forced upwards by the rear end of hook l i until the block [2 can slip off the hook i i provided the fall 25 is payed out. Also in this case, the nut 18 acts as a brake to retard the swinging movement of hook I I.

In accordance with Fig. 4, the pivot M of the hook member H is located about centrally between the front and the rear end thereof. top face 3! of the rear portion of member i! here forms a runway for a disk 32 eccentrically mounted on a shaft 33 suported in bearings 36 of the davit head 8 and provided with a hand lever 35, which is normally locked by a pin 35a. In the position shown in full lines, the runway ii is tangent to disk 32 at a point 32a, the diameter of which passes through the axis of shaft 33, so that the thrust of the hook member II has no tendency to rotate the disk. However, if lever 35 is unlocked and turned, by the crew in the boat, through a small angle in clockwise direction, the thrust of hook member l I on disk 32 will cause further rotation of said disk, whereby the hook member I l is swung under the gravity pull of the boat, in clockwise direction so as to allow the block IE to slip off, said swinging movement being braked by the disk 32.

Fig. illustrates a preferred embodiment, wherein the hook member I I is integral with the davit head 8a, which is pivoted as at is to the davit arm 8. Rotatably mounted in the davit head is sheave 26, over which is passed the boat fall 25 running to the block I 2. Nut I8 is pivotally mounted, through trunnions 19, in a bracket 20 The I on the davit arm 8, and cooperating with this nut is the threaded portion of spindle H, the non-threaded portion of which is supported by a bracket 36 on the davit head 8a. Mounted at the free end of spindle I7 and engaging bracket 36 is a handwheel 29 normally prevented from rotation by a hook 37 hinged to the head 8a and locked by a pin 38. It will be appreciated that, with locking pin 38 removed and hook 3:"! swung back, the gravity pull of the boat will cause the davit head to swing down against the retarding action of the nut l8 on the spindle I1. If necessary, the handwheel may be rotated a few turns by the crew in the boat to initiate the automatic outward movement of the spindle.

What I claim is:

1. In combination with a gravity davit having a body portion, a member supporting a life boat, said member being pivoted to the body portion of the said davit and swinging in downward direction relative to said body portion under the gravity pull of the life boat suspended therefrom, an element associated both with said memher and with said body portion of said davit, said element being displaced under the action of said gravity pull, brake means cooperating with said element and secured to said body portion for counteracting the displacement of said element, and releasable means secured to said body portion for locking said element against displacement thereof relative to said counteracting means.

2. In combination with a gravity davit having a body portion, a hook member, supporting a life boat, said member being pivoted to the body portion of the said davit and swinging in downward direction relative to said body portion under the gravity pull of the life boat suspended therefrom, a screw spindle flexibly coupled with said hook member, a nut pivotally mounted on said body portion of the davit so as to be fixed against rotation about its axis and cooperating with said screw spindle, and releasable means secured to said body portion for locking said spindle against rotation relative to said nut.

3. In combination with a gravity davit having a body portion, a hook member supporting a life boat, said hook member being pivoted to the body portion of 'the said davit and swinging in downward direction relative to said body under the gravity pull of the life boat suspended therefrom, a disk rotatably mounted on an eccentric axis and secured to said body portion of the davit and said disk being in engagement with a face of said hook member, said disk being normally in self-locking position thereby preventing said hook member from swinging motion under the gravity pull of the life boat, a hand lever connected to said eccentric disk and adapted to turn said disk into unlocking position thereby starting the swinging motion of the hook member, and releasable means secured to said body portion for locking said hand lever in the self-locking position of the disk.

4. The combination, as set forth in claim 1, in which said element comprises a screw-spindle of the non-self braking type and said means associated with the body portion for counteracting the displacement of the screw spindle comprises a nut cooperating with the latter.

5. In combination with a gravity davit having a body portion, a member supporting a life boat, said member being pivoted to the body portion of the said davit and swinging in downward direction relative to said body portion under the gravity pull of the life boat suspended therefrom,

an element associated both with said member and with said body portion of said davit, said element being displaced under the action of said gravity pull, means cooperating with said element and secured to said body portion for counteracting the displacement of said element, and releasable means secured to said body portion for locking said element against displacement thereof relative to said counteracting means. I

ADRIANUS VREUGDENHIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Schat Apr. 22, 1941 

